1. Field of the Invention
This invention relates generally to a pickup cartridge, and more particularly to a novel pickup cartridge of the moving coil type.
2. Description of the Prior Art
In a conventional moving coil type pickup cartridge, a moving coil is wound on a substantially square armature or on a cruciform armature having four projections. In detail, the armature is of a substantially square shape with one of its diagonals being disposed vertically. A cantilever arraying a stylus on its foremost end is fixed at its rear end to the center of the armature. A first coil for the right channel signal and a second coil for the left channel signal are wound on the armature. The armature is disposed in a magnetic field which is established by a permanent magnet and a yoke. In such a conventional pickup cartridge, it may be apparent that the afore-mentioned armature has a large mass due to its shape. Accordingly, an equivalent compliance of the stylus tip is small. Further, a large area of the armature necessitates a large cross sectional area of the gap between the yokes in the magnetic circuit. In addition, the magnetic reluctance of the magnetic circuit passing through the yoke is made greater due to an aperture formed in the yoke for the cantilever which extends therethrough, so that the magnetic flux density in the gap can not be made great. Further, due to the fact that the cantilever is formed in the armature, it often is difficult and expensive to replace the cantilever with a new one.
Another conventional pickup cartridge of the moving coil type consists of separate coils for the left and right channels and separate magnetic circuits for the respective coils. The magnetic circuits are formed of a permanent magnet and a yoke. The coils are wound in the gap formed in the yoke. The pickup cartridge of this type is relatively small in mass, but since the entireties of the coils are not disposed in the gap, the output signal is small and the magnetic reluctance of the magnetic circuit is not low.